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Message-ID: <ZRQfyNX9WsvmpZ1r@smile.fi.intel.com>
Date: Wed, 27 Sep 2023 15:27:52 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
Jonathan Cameron <jic23@...nel.org>,
Lars-Peter Clausen <lars@...afoo.de>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Angel Iglesias <ang.iglesiasg@...il.com>,
Andreas Klinger <ak@...klinger.de>,
Benjamin Bara <bbara93@...il.com>,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/5] tools: iio: iio_generic_buffer ensure alignment
On Wed, Sep 27, 2023 at 11:26:07AM +0300, Matti Vaittinen wrote:
> The iio_generic_buffer can return garbage values when the total size of
> scan data is not a multiple of the largest element in the scan. This can be
> demonstrated by reading a scan, consisting, for example of one 4-byte and
> one 2-byte element, where the 4-byte element is first in the buffer.
>
> The IIO generic buffer code does not take into account the last two
> padding bytes that are needed to ensure that the 4-byte data for next
> scan is correctly aligned.
>
> Add the padding bytes required to align the next sample with the scan size.
...
> + /*
> + * We wan't the data in next sample to also be properly aligned so
Pardon me, won't or want, I didn't get?..
> + * we'll add padding at the end if needed.
> + *
> + * Please note, this code does ensure alignment to maximum channel
> + * size. It works only as long as the channel sizes are 1, 2, 4 or 8
> + * bytes. Also, on 32 bit platforms it might be enough to align also
32-bit
> + * the 8 byte elements to 4 byte boundary - which this code is not
8-byte
4-byte
> + * doing.
> + */
--
With Best Regards,
Andy Shevchenko
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